Zastosowanie "Beva-371" do dublowania obrazów

In the last fifteen, twenty years, modern conservation used to employ various products or chemical semi-products whose properties complied to the requirements of conservators. Only just recently some companies that cooperate with conservators have undertaken the manufacture of products to be used specially to preserve works of art. One of such products is a thermoplastic adhesive known as BEVA 371, developed by Gustaw A. Berger in' the United States. The author of this paper had to his dispodsal a licensed Swiss product. Until today waxen mass was used most frequently to ply up paintings; however, depending on the composition, it has adverse effects upon conserved paintings. One of the disadvantages of waxen mass is a high acid number, then a high coefficient of light refraction and also ability to crystallization (especially in wet and cool interiors of churches), which leads to the desizing of plyed-up paintings. BEVA 371, mentioned above, is deprived of those disadvantages. Its use to ply up paintings in the Monuments Conservation Workshop in Gdansk has been preceded by a number of the socalled blind trials, which gave positive results confirming advantages of the adhesive. BEVA 371 was used to ply up three altar paintings from the 18th century, painted in oil technique on canvas, found in the church at Ostrowiec. The paintings had been preserved before in the 19th century and at that time flour paste was used for plying up but it got mouldy in damp conditions prevailing in the church. This brought about a deplying of the paintings and worsening of the condition of the canvas of subpainting. Because right after the conservation the paintings were to be pu back in the church, it was necessary to use BEVA 371 which had no disadvantages of waxen mass of flour paste. The paintings were prepared for plying-up in the following way: they were taken from frames and a plying-up canvas was removed. The remains of the flour paste were taken from the reverse, while crackings in the facing were protected with paper glued with polyvinyl alcohol. Only then they started putting BEVA 371 on the reverse of the painting and on plying-up canvas stretched on the frame. Just as treated pictures had a smooth painting layer, their plying-up could be done without a special plying-up table. The plying-up was done on a simple table covered with polyester foil on which the painting was put with its face downwards; on it a plying-up canvas was put which was pressed by parts with an electric thermo- regulated iron and additonally pressed and cooled with marbles. As could be found out during the trials and plying-up, the process of gluing can be carried out in a long time distance, after the placing of the preparation on the object. And in this lies a positive property of BEVA 371, namely its thermoplasticity. After the process of gluing had been completed, further procedure was carried out in a traditional way, with only one small modification: to make up the missing parts the putty, based on BEVA 371, with a filler, was used. As has been found out. this adhesive may be employed on a large scale to protect and to glue a painter’s layer and various kinds of plying-ups such as sandwich.